A variety of different hosts including plants, algae, fungi, stramenopiles and yeast are being investigated as means for commercial polyunsaturated fatty acid [“PUFA”] production. Genetic engineering has demonstrated that the natural abilities of some hosts (even those natively limited to linoleic acid [LA; 18:2 omega-6] and α-linolenic acid [ALA; 18:3 omega-3] fatty acid production) can be substantially altered to result in high-level production of various long-chain omega-3/omega-6 PUFAs. Whether this is the result of natural abilities or recombinant technology, production of arachidonic acid [ARA; 20:4 omega-6], eicosapentaenoic acid [EPA; 20:5 omega-3] and docosahexaenoic acid [DHA; 22:6 omega-3] may all require expression of a delta-5 desaturase gene.
Thus, the instant invention concerns new delta-5 desaturases having high activity that are well suited for integration into PUFA biosynthetic pathways in commercially useful host cells.